Preparation of COF-LZU1/PAN membranes by an evaporation/casting method for separation of dyes

Covalent organic frameworks (COFs) have attracted lots of attention in membrane separation due to their large surface area, well-defined pore structure and good thermal stability. In this work, evaporation/casting method was performed to fabricate COF-LZU1 membranes. p-Phenylenediamine (PDA) powder and 1,3,5-benzenetricarboxaldehyde (TFB) solution were alternatively evaporated and cast onto polyacrylonitrile (PAN) membrane to prepare COF-LZU1 membranes and employed for the separation of dyes. The effects of PDA evaporation temperature, time, layer number and reactant amount in each COF-LZU1 layer were studied, and the long-term operation was evaluated. The COF-LZU1 membranes showed remarkable rejection (> 90%) for different dyes (Mw 350-800), low rejectionn(< 8%) for salts and high solvent permeance (> 500 L m(-2) h(-1) MPa-1). The COF-LZU1 membrane also displayed excellent long-term operation stability, suggesting potential for rejection and desalination of dyes. Graphic abstract Evaporation/casting method was employed for fabrication of COF-LZU1 membranes, and the membranes displayed high rejection (>90%) for different dyes (Mw 350-800) and solvent permeance (> 500 L m(-2)h(-1)MPa(-1)), and low rejection (<8%) for salts, suggesting potential for rejection and desalination of dyes solutions.